Thumbscrew for pluggable modules

ABSTRACT

In one example, a pluggable module comprises a shell, a module connector, and one or more thumbscrews. The shell defines a cavity within which a PCB and one or more components are disposed and includes a front, back, first side, and second side. The module connector is operatively connected to the PCB near the back of the shell and extends from within the cavity to outside the shell through an opening defined in the back of the shell. The module connector is configured to operatively couple the pluggable module to a host device. The thumbscrews are housed within one or more portions of the shell and are configured to threadably secure the pluggable module to the host device. Each of the thumbscrews comprises a torque limiter. The pluggable module can further comprise protecting means for protecting a portion of the module connector extending outside the cavity from damage.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention generally relates to pluggable electronic andoptoelectronic modules and host devices. In particular, some exampleembodiments relate to thumbscrews for securing pluggable modules to hostdevices.

2. The Related Technology

Conventional mechanical platforms implemented in optical and electricalnetworks include a pluggable module configured to be plugged into a hostdevice to convert electrical data signals to optical data signals andvice versa. Specific functionality, dimensions, and/or otherfunctionality of such mechanical platforms are often standardized by amulti-source agreement (“MSA”), such as the X2 MSA, XPAK MSA, and/orXENPAK MSA, for example.

Traditional pluggable modules, including X2, XPAK, and XENPAKform-factor modules, include a narrow channel defined along oppositesides of the module that run the length of the module. Host devicesinclude corresponding narrow guiderails. To plug such a module into ahost device, the module channels are aligned with the host guiderailsand the module is pushed into the host device, the module channelsengaging the host guiderails to ensure proper alignment of the modulewithin the host device. Once plugged in, a module connector in the backof the module and a host connector in the host device provide anelectrical interface between the module and the host device.

Pluggable modules typically include a hard shell that can protect theinternal components of the pluggable module from shock damage duringhandling, assembly, or the like. In some form-factors, however, aportion of the module connector extends outside the confines of theshell. The portion extending outside the confines of the shell can besusceptible to damage from shocks or impacts.

Additionally, some pluggable modules, like XENPAK form-factor modules,are secured in host devices by two short thumbscrews which engagethreaded receptacles in the front panel of the host device. Thethumbscrews typically rely on a human user to provide tightening torquevia the thumbscrew head. Achieving consistent torque load for allthumbscrews can be difficult as different users may apply differenttorques to the thumbscrews. Thumbscrews that are over-tightened can bedamaged or can cause damage to other components. Thumbscrews that areunder-tightened can result in poor connections between the pluggablemodule and the host device.

To facilitate the use of thumbscrews, the module typically includes anoversize module front panel with two flanges that extend outward fromopposing sides of the module, one thumbscrew being inserted through eachflange. The flanges typically overlap a significant amount of the hostfront panel to provide enough metal for the thumbscrews to thread into.The overlap is increased by the requirement that the thumbscrews avoidthe space behind the module front panel and the host front paneloccupied by the module itself and the narrow guiderails of the hostdevice.

As a result of the required overlap, the footprint of the module frontpanel and flanges extends significantly beyond the footprint of the mainbody of the module as viewed from the front of the module. Consequently,the maximum number of modules that can be plugged into a single hostdevice is limited by the module front panel and flanges, and not by themain body of the module.

Further, the attachment of traditional pluggable modules to the frontpanel of the host device can make containment of electromagneticinterference (“EMI”) at the back of the module difficult to achieve.Specifically, attaching the module to the front panel of the host devicecan result in a good EMI seal between the module flange and the hostfront panel. However, tolerance stack-up in the plugging directionresults in a highly variable position of the module connector withrespect to the host connector from one module to another such that aconventional elastomeric EMI gasket, which has a limited compressionrange, positioned between the back of the module and the host connectoris inadequate for providing EMI containment.

Additionally, the tolerance stack-up is typically compensated for byincreasing the length of contacts within the module connector and/orhost connector. The increased contact length allows for greatervariation in the position of the module connector with respect to thehost connector. Additionally, however, the increased contact lengthincreases EMI emissions of each lengthened contact and can result inlarge contact stubs that extend beyond the points of contact betweencontacts in the module connector and contacts in the host connector. Thelarge stubs create inductive discontinuities that degrade high speedsignal integrity and further exacerbate EMI emissions.

On the other hand, the back of the module can be secured directly to thehost connector, rather than securing the module front panel directly tothe host front panel, to improve the EMI seal at the interface betweenthe back of the module and the host connector. Such an arrangement wouldadditionally allow shorter contact lengths to be used in the moduleconnector and host connector as tolerance stack-up would not be an issueat that interface. However, the tolerance stack-up would then have to bedealt with at the interface between the module front panel and the hostfront panel, preventing the module front panel from being directlysecured to the host front panel and compromising the EMI seal at thatinterface.

Additionally, some MSAs specify belly-to-belly configurations where afirst module is positioned on top of a host printed circuit board(“PCB”) and a second module is positioned upside down on the bottom ofthe host PCB directly beneath the first module. In such a configuration,the two modules are usually separated by only a few millimeters, orlittle more than the thickness of the host PCB. The presence of theoversized module front panel in the X2, XENPAK and other pluggablemodules precludes belly-to-belly configurations with these modules sincethe oversized module front panel prevents the modules from beingpositioned sufficiently close together.

The subject matter claimed herein is not limited to embodiments thatsolve any disadvantages or that operate only in environments such asthose described above. Rather, this background is only provided toillustrate one exemplary technology area where some embodimentsdescribed herein may be practiced

BRIEF SUMMARY OF SOME EXAMPLE EMBODIMENTS

In general, example embodiments relate to pluggable modules that includethumbscrews or other features or aspects for protecting a connector ofthe pluggable module from damage and/or for ensuring consistent torqueloads during installation in a host device.

In one example embodiment, a pluggable module comprises a shell, amodule connector, and one or more thumbscrews. The shell defines acavity within which a PCB and one or more components are disposed andincludes a front, back, first side, and second side. The moduleconnector is operatively connected to the PCB near the back of the shelland extends from within the cavity to outside the shell through anopening defined in the back of the shell. The module connector isconfigured to operatively couple the pluggable module to a host device.The thumbscrews are housed within one or more portions of the shell andare configured to threadably secure the pluggable module to the hostdevice. Each of the thumbscrews comprises a torque limiter. Thepluggable module can further comprise protecting means for protecting aportion of the module connector extending outside the cavity fromdamage.

In another example embodiment, a thumbscrew for securing a pluggablemodule to a host device comprises a head defining an opening. Thethumbscrew further comprises a shaft defining a first end and a secondend. The first end includes a threaded portion configured to threadablyengage a tapped hole of the host device and the second end extends atleast partially into the opening of the head. The thumbscrew furthercomprises a torque limiter that substantially prevents application oftightening torques that exceed a predetermined maximum torque to theshaft when the threaded portion threadably engages the tapped hole.

In yet another example embodiment, a thumbscrew for securing a pluggablemodule to a host device comprises a shaft, a threaded portion and ahead. The shaft defines a first end and a second end oppositely disposedfrom the first end. The threaded portion is formed in the first end andis configured to threadably secure the pluggable module to the hostdevice. The pluggable module includes a module connector configured tomate with a host connector of the host device. The head is disposed onthe second end of the shaft and is configured to apply at least sometorque applied to the head to the shaft. The first end of the shaft isconfigured to cooperate with a shell of the pluggable module to form aprotective barrier for the module connector.

Additional features of the invention will be set forth in thedescription which follows, and in part will be obvious from thedescription, or may be learned by the practice of the invention. Thefeatures of the invention may be realized and obtained by means of theinstruments and combinations particularly pointed out in the appendedclaims. These and other features of the present invention will becomemore fully apparent from the following description and appended claims,or may be learned by the practice of the invention as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other features of the presentinvention, a more particular description of the invention will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 discloses an example mechanical platform including a host deviceand a pluggable module;

FIGS. 2A-2C disclose one example embodiment of a pluggable module;

FIGS. 3A and 3B disclose another example embodiment of a pluggablemodule;

FIGS. 4A-4D disclose an example embodiment of a thumbscrew withintegrated torque limiter that can be implemented to threadably secure apluggable module to a host device;

FIG. 5 discloses an example host bezel assembly that can be implementedin the host device of FIG. 1;

FIG. 6 discloses an example host guide that can be implemented in thehost device of FIG. 1;

FIG. 7A discloses an example host connector such as may be employed inthe host device of FIG. 1; and

FIG. 7B discloses an example connector cover that can be implemented inthe host connector of FIG. 7A.

DETAILED DESCRIPTION

The principles of the embodiments described herein describe thestructure and operation of several examples used to illustrate thepresent invention. It should be understood that the drawings arediagrammatic and schematic representations of such example embodimentsand, accordingly, are not limiting of the scope of the presentinvention, nor are the drawings necessarily drawn to scale. Well-knowndevices and processes have been excluded so as not to obscure thediscussion in details that would be known to one of ordinary skill inthe art.

Some example embodiments of the invention relate to pluggable modulesthat include thumbscrews or other features or aspects for protecting aconnector of the pluggable module from damage and/or for ensuringconsistent torque loads during installation in a host device. Forinstance, the thumbscrews can include a torque limiter to achieveconsistent torque loads. Alternately or additionally, the thumbscrewscan include an extension to form a protective barrier around theconnector. Alternately or additionally, the pluggable modules caninclude extensions to form a protective barrier around the connector.

The embodiments disclosed herein may be implemented in various types ofelectronic and optoelectronic modules of various operating speeds andvarious form factors, including, but not limited to, the emerging 100GForm-factor Pluggable (“CFP”) Multi-Source Agreement (“MSA”) formfactor. As used herein, the term “optoelectronic module” includesmodules having both optical and electrical components. Examples ofoptoelectronic modules include, but are not limited to transponders,transceivers, transmitters, and/or receivers. Optoelectronic modules canbe used, for instance, in telecommunications networks, local areanetworks, metro area networks, storage area networks, wide areanetworks, and the like.

I. EXAMPLE MECHANICAL PLATFORM

With reference first to FIG. 1, an example mechanical platform 100 isdisclosed according to some embodiments of the invention. The mechanicalplatform 100 includes a pluggable optoelectronic module 102 (“module102”) and a host device 104. The module 102 is configured to be pluggedinto the host device 104 as will be explained in more detail to follow.

The host device 104 includes a heatsink 106, front panel 108, host bezelassembly 110, host PCB 112, host guides 114A, 114B (not shown), and hostconnector 116. In some embodiments, a plurality of shoulder screws118A-118D removably secure the heatsink 106 to the host device 104.Optionally, a compression spring 120A-120D can be circumferentiallydisposed about each of the shoulder screws 118A-118D, respectively. Thecompression springs 120A-120B are configured to bias the shoulder screws118A-118D upwards (e.g., in the positive y-direction) away from the hostguides 114A, 114B. When the shoulder screws 118A-118D are aligned withcorresponding tapped holes on host guides 114A and 114B, a user canexert a downward force (e.g., in the negative y-direction) on shoulderscrews 118A-118D to overcome the upward bias from compression springs120A-120D to install the shoulder screws 118A-118D into thecorresponding tapped holes on the host guides 114A and 114B. Onceinstalled, the compression springs 120A-120D serve to bias the heatsink106 against the top surface of the module 102. Although not shown, athermal pad, thermal film, thermal gel, and/or other thermallyconductive material can be placed between the module 102 and heatsink106 to thermally couple the heatsink 106 to the module 102 and improvethe ability of the heatsink 106 to receive and dissipate heat away fromthe module 102.

II. FIRST EXAMPLE PLUGGABLE MODULE

With additional reference to FIGS. 2A-2C, aspects of a first examplepluggable module 200 (“module 200”) are disclosed. The module 200 maycorrespond to the module 102 of FIG. 1. As shown, the module 200includes a shell assembly 202 comprising top shell 204 and bottom shell206. Alternately, a monolithic shell can be implemented instead of ashell assembly 202. The top and/or bottom shell 204, 206 can be madeusing any reasonable material known in the art. The shell assembly 202includes a front 202A, back 202B, first side 202C, and second side 202D.

The shell assembly 202 defines a cavity within which a module PCB (notshown) is disposed. One or more electronic, optical, and/oroptoelectronic components can be coupled to the module PCB and disposedwithin the cavity, including a transmitter optical subassembly (“TOSA”),receiver optical subassembly (“ROSA”), laser driver, post amplifier,controller, or the like or any combination thereof.

A module connector 208 is operatively coupled to the module PCB andextends from within the cavity defined by the shell assembly 202 tooutside the shell assembly 202 through an opening defined in the back202B of the shell assembly 202. The module connector 208 is configuredto mate with a corresponding host connector, such as the host connector116 of FIG. 1, when the module 200 is plugged into a host device and tooperatively couple the module 200 to the host device.

Guiderails 210, 212 protrude laterally at the junction of the top shell204 and bottom shell 206 from opposite sides 202C, 202D of the module200 and extend along the length of the module 200. However, it is notrequired that the guiderails 210, 212 protrude laterally at the junctionof the top shell 204 and bottom shell 206. For instance, the guiderails210, 212 can protrude from opposite sides 202C, 202D of the module 200above or below the junction of the top and bottom shells 204, 206 orfrom opposite sides of a module that includes a monolithic shell ratherthan a shell assembly 202. The guiderails 210, 212 are configured toengage channels on a host bezel assembly 110 (FIG. 1) and host guides114A, 114B (FIG. 1), as will be discussed in more detail below.

Thumbscrews 214 and 216 are housed within guiderails 210, 212 andprotrude through the front 202A of the shell assembly 202 and extendalong the full length of the module 200. The thumbscrews 214 and 216 areconfigured to threadably secure the module 200 to a host device in whichthe module 200 is received. In some embodiments, each of the thumbscrews214, 216 comprise hardened steel. Alternately or additionally, each ofthe thumbscrews 214, 216 can be configured to absorb impact forces toprotect the module connector 208 during handling, assembly, or the like.

As shown in FIG. 2B, thumbscrew 214 comprises a shaft 218 defining afirst end 218A and a second end 218B. Similarly, thumbscrew 216comprises a shaft 220 defining a first end 220A and a second end 220B.Each of the first ends 218A, 220A includes a threaded portion 222, 224,respectively, formed thereon. The threaded portions 222, 224 areconfigured to threadably secure the pluggable module 200 to a hostdevice.

As shown in FIG. 2B, each of the first ends 218A, 220A further includesan extension 226, 228, respectively, configured to cooperate with thebottom shell 206 to form a protective barrier for the module connector208, as depicted in FIG. 2A. As such, the extensions 226, 228 serve asone example of a structural implementation of a means for protecting aportion of the module connector 208 extending outside the cavity of theshell assembly 202 from damage.

Turning back to FIG. 2B, each of the second ends 218B, 220B includes ahead 230, 232 disposed on the second end 218B, 220B, respectively, andconfigured to extend outside of shell assembly 202 so as to beaccessible to a user, as depicted in FIG. 2A. In the example of FIG. 2B,the heads 230, 232 are integrally formed with the shafts 218, 220 at thesecond ends 218B, 220B. As such, the heads 230, 232 are configured toapply torques to the shafts 218, 220 in response to torques applied tothe heads 230, 232. Alternately, the heads 230, 232 can be separablefrom the shafts 218, 220. Optionally, one or both of thumbscrews 214,216 can include a torque limiter, as will be discussed in more detailwith respect to FIGS. 4A-4D.

During assembly and handling of pluggable modules, the pluggable modulescan be subjected to various impact forces. Conventional pluggablemodules having a module connector that extends outside the shell of theconventional pluggable module can be damaged from such impact forces.For instance, depending on the magnitude and location of the impact, themodule connector in a conventional pluggable module can partially orcompletely decouple from the module PCB, or can be chipped, cracked, orotherwise damaged from the impact.

According to some embodiments of the invention, however, the module 200can include thumbscrews 214, 216 comprising extensions 226, 228 whichextend outwardly beyond the back end of the module connector 208. Asbest seen in FIGS. 2A and 2C, the extensions 226, 228 cooperate with thebottom shell 206 to form a protective barrier for the module connector208.

The protective barrier is generally designated in FIG. 2C by referenceline 234. The region inside the protective barrier 234, including themodule connector 208, can be protected against various impact forces bythe extensions 226, 228 and bottom shell 206. For instance, theextensions 226, 228 and bottom shell 206 can protect the moduleconnector 208 against flat impact forces near the back 202B of module200 from substantially planar surfaces. In particular, any substantiallyplanar surface that is wider than the distance between the corner of thebottom shell 206 and the ends of the extensions 226, 228 forming theprotective barrier 234 cannot cross the protective barrier 234. Instead,any impact against such a substantially planar surface can be absorbedby the extensions 226, 228 and/or bottom shell 206. Alternately oradditionally, the extensions 226, 228 and bottom shell 206 can beconfigured to protect the module connector 208 against other types ofimpact forces.

In some embodiments, a compression spring (not shown) can becircumferentially disposed about each thumbscrew 214, 216 and housedwithin guiderail 210, 212, respectively. The compression springs can beconfigured to bias the thumbscrews 214, 216 in an outward position asshown in FIGS. 2A and 2C, which may be approximately 6 millimeters(“mm”) in some embodiments. Prior to plugging the module 200 into a hostdevice, the threaded portions 222, 224 of thumbscrews 214, 216 can beretracted into the guiderails 210, 212 due to the outward bias forceexerted by the compression springs. However, even if the thumbscrews214, 216 are outwardly biased by compression springs, the extensions226, 228 can be sufficiently long to form the protective barrier 234 forthe module connector 208 with the bottom shell 206.

Returning to FIG. 2A, the module 200 additionally includes an EMI collar236 surrounding the front 202A of the module 200. The EMI collar 236operates in conjunction with a host bezel assembly to create an EMIshield around the front 202A of the module 200 when plugged into a hostdevice.

Optionally, the top shell 204 of module 200 can include an integratedlow profile heatsink for low profile, low power applications.

Additional aspects regarding example pluggable modules that can beimplemented in CFP and other mechanical platforms are disclosed in U.S.patent application Ser. No. 12/203,027, filed Sep. 2, 2008 and entitledCFP MECHANICAL PLATFORM (referred to herein as “the '027 application”).The '027 application is herein incorporated by reference in itsentirety.

III. SECOND EXAMPLE PLUGGABLE MODULE

Turning now to FIGS. 3A and 3B, aspects of a second example pluggablemodule 300 (“module 300”) are disclosed. The module 300 may correspondto the module 102 of FIG. 1. The module 300 is similar in some respectsto the module 200 of FIG. 2 and includes a shell assembly 302 comprisingtop shell 304 and bottom shell 306. Alternately, module 300 can includea monolithic shell. The shell assembly 302 includes a front 302A, back302B, first side 302C, and second side 302D. The shell assembly 302defines a cavity within which a module PCB (not shown) and one or morecomponents (not shown) are disposed.

A module connector 308 is operatively coupled to the module PCB andextends from within the cavity defined by the shell assembly 302 tooutside the shell assembly 302 through an opening defined in the back302B of the shell assembly 302. The module connector 308 is configuredto mate with a corresponding host connector, such as the host connector116 of FIG. 1, when the module 300 is plugged into a host device and tooperatively couple the module 300 to the host device.

Guiderails 310, 312 protrude laterally at the junction of the top shell304 and bottom shell 306 from opposite sides 302C, 302D of the module300 and extend along the length of the module 300. However, it is notrequired that the guiderails 310, 312 protrude laterally at the junctionof the top shell 304 and bottom shell 306. The guiderails 310, 312 areconfigured to engage channels on a host bezel assembly 110 (FIG. 1) andhost guides 114A, 114B (FIG. 1), as will be discussed in more detailbelow.

Thumbscrews 314 and 316 are housed within guiderails 310, 312 andprotrude through the front 302A of the shell assembly 302 and extendalong the full length of the module 300. The thumbscrews 314 and 316 areconfigured to threadably secure the module 300 to a host device in whichthe module 300 is received. In some embodiments, each of the thumbscrews314, 316 comprise hardened steel. Optionally, a compression spring (notshown) can be circumferentially disposed about each thumbscrew 314, 316and housed within guiderail 310, 312, respectively, to bias thumbscrews314, 316 in an outwards position prior to plugging the module 300 into ahost device.

Each thumbscrew 314, 316 includes a shaft defining a first end and asecond end, with a threaded portion 318, 320 formed in the shaft at thefirst end and a head 322, 324 disposed on the shaft at the second end.The head 322, 324 can be integrally formed with the shaft of eachthumbscrew 314, 316, or separable from each shaft. Optionally, one orboth of the thumbscrews 314, 316 can include a torque limiter, as willbe discussed in more detail with respect to FIGS. 4A-4D.

To protect the module connector 308 from impact forces according to someembodiments of the invention, each of guiderails 310, 312 can include anextension 310A, 312A extending outwardly beyond the back end of themodule connector 308. In some embodiments, the extensions 310A, 312A canpartially surround portions of thumbscrews 314, 316 housed therein.Alternately, the extensions 310A, 312A can completely surround portionsof thumbscrews 314, 316 housed therein.

The extensions 310A, 312A cooperate with the bottom shell 306 to form aprotective barrier for the module connector 308. As such, the extensions310A, 312A serve as a second example of a structural implementation of ameans for protecting a portion of the module connector 308 extendingoutside the cavity of the shell assembly 302 from damage.

The protective barrier formed by extensions 310A, 312A and bottom shell306 is generally designated in FIG. 3B by reference line 326. Analogousto the explanation given above with respect to FIG. 2C, the regioninside the protective barrier 326, including the module connector 308,can be protected against various impact forces by the extensions 310A,312A and bottom shell 306. For instance, the extensions 310A, 312A andbottom shell 306 can protect the module connector 308 against flatimpact forces near the back 302B of module 300 from substantially planarsurfaces. Alternately or additionally, the extensions 310A, 312A andbottom shell 306 can be configured to protect the module connector 308against other types of impact forces.

Returning to FIG. 3A, the module 300 additionally includes anelectromagnetic interference (“EMI”) collar 328 surrounding the front302A of the module 300. The EMI collar 328 operates in conjunction witha host bezel assembly to create an EMI shield around the front 302A ofthe module 300 when plugged into a host device. Optionally, the topshell 304 of module 300 can include an integrated low profile heatsinkfor low profile, low power applications.

IV. THUMBSCREW TORQUE LIMITER

With additional reference to FIGS. 4A-4D, an example embodiment of athumbscrew 400 with integrated torque limiter is disclosed. Embodimentsof the example thumbscrew 400 can be implemented in the modules 102,200, 300 of FIGS. 1, 2A, and 3A, for instance, or in other pluggablemodules or other environments altogether.

FIG. 4A discloses an exploded view of thumbscrew 400 and FIG. 4Bdiscloses a perspective view of one end of the thumbscrew 400 with thepieces shown in FIG. 4A fully assembled. As shown in FIG. 4A, thethumbscrew 400 comprises a shaft 402 defining a first end 402A and asecond end 402B oppositely disposed from the first end 402A. The firstend 402A can include a threaded portion configured to threadably securea pluggable module in which the thumbscrew 400 is implemented to a hostdevice. For instance, the threaded portion of first end 402A canthreadably engage a tapped hole of the host device. As used herein,“tapped hole” refers to a through-hole or a cavity that containsinternal threads.

The second end 402B can include a shaft head 404. The thumbscrew 400further comprises a screw head 406 that is slidable along the shaft 402to engage the shaft head 404 at the second end 402B of the shaft 402. Asshown in FIG. 4C, the screw head 406 defines an opening 408 configuredto receive head 404 of the shaft 402. In particular, the second end 402Bof shaft 402 can at least partially extend into the opening 408, asshown in FIG. 4B. In some embodiments, the screw head 406 includes astepped bezel 410 configured to engage the shaft head 404 tosubstantially prevent the screw head 406 from moving in the positivez-direction with respect to the shaft 402 when the thumbscrew 400 isfully assembled.

One or both of the shaft 402 and screw head 406 can comprise injectionmolded metal, forged metal, machine turned metal, broached metal, or thelike or any combination thereof

Optionally, as shown in FIGS. 4A and 4B, the thumbscrew 400 can furthercomprise a notch 412 formed in the shaft 402, and a retaining clip 414.The retaining clip 414 can cooperate with the notch 412 to substantiallyconfine the second end 402B of the shaft 402 within the opening 408 ofthe screw head 406. During assembly, the first end 402A of the shaft 402is inserted into the screw head 406. The screw head 406 is slid alongshaft 402 to the second end 402B. The shaft head 404 can substantiallyprevent the screw head 406 from moving in the positive z-direction,while the notch 412 and retaining clip 414 can substantially prevent thescrew head 406 from moving in the negative z-direction. The thumbscrew400 further comprises a torque limiter that substantially preventsapplication of tightening torques that exceed a predetermined maximumtorque to the shaft when the threaded portion of the first end 402Athreadably engages a tapped hole of a host device. As used herein,“tightening torque” refers to a torque that tends to tighten a screw orother threaded fastener into a device having a tapped hole. Thetightening torque may be clockwise or counterclockwise, depending onwhether the threaded portion on the first end 402A of thumbscrew 400includes clockwise or counterclockwise threads.

Generally, the torque limiter of thumbscrew 400 can include one or morecomponents integrally formed in the shaft 402, screw head 406, or both.Alternately or additionally, the torque limiter of thumbscrew 400 caninclude one or more components that are separate from the shaft 402 andscrew head 406.

In some embodiments, the torque limiter of thumbscrew 400 includes oneor more cantilever springs 416 extending from the base of screw head406, as seen in FIG. 4C, and one or more cams 418 radially protrudingfrom the second end 402B of the shaft 402, as seen in FIG. 4B. Thecantilever springs 416 are configured to selectively engage the cams 418and apply a tightening torque applied to the screw head 406 to the shaft402 depending on whether the tightening torque applied to the screw headexceeds the predetermined maximum torque.

Accordingly, when the tightening torque applied to the screw head 406 isless than or equal to the predetermined maximum torque, the cantileversprings 416 can engage the cams 418 and apply the tightening torque tothe shaft 402. In contrast, when the tightening torque applied to thescrew head 406 exceeds the predetermined maximum torque, the cantileversprings disengage from the cams and do not apply the tightening torqueto the shaft 402.

With additional reference to FIG. 4D, a simplified cross-section of thethumbscrew 400 is disclosed that omits the retaining clip 414. In theembodiment of FIG. 4D, the thumbscrew 400 includes four cantileversprings 416 and four cams 418. Alternately or additionally, thethumbscrew 400 can include as few as one cantilever spring and one cam,or more than four cantilever springs and four cams.

In some embodiments, the predetermined maximum torque of the torquelimiter may depend on the quantity of cantilever springs and camsincluded in the thumbscrew 400. Accordingly, thumbscrew designers mayselect a specific number of cantilever springs and cams to include in athumbscrew design based on a desired predetermined maximum torque.

With continuing reference to FIG. 4D, each of the cams 418 comprises alead-in feature 418A and is characterized by a distance D that the cam418 radially protrudes from the second end 402B of the shaft 402. Eachof the lead-in features 418A can have a positive shape, meaning thelead-in features 418A slope away from the adjacent cantilever spring 416to facilitate disengaging the cantilever springs 416 from the cams 418when the tightening torque exceeds the predetermined maximum torque.

Upon application of a tightening torque, e.g., a clockwise torque in theexample of FIGS. 4A-4D, to the screw head 406, the cantilever springs416 extending from the base of the screw head 406 engage the lead-infeatures 418A of each cam 418 when the tightening torque is less thanthe predetermined maximum torque and apply the torque to the shaft 402.However, when the tightening torque exceeds the predetermined maximumtorque, the cantilever springs 416 can resiliently deflect up and overadjacent lead-in features 418A to disengage from the cams 418.

Further, each cam 418 can additionally comprise a trailing feature 418Boppositely disposed from the lead-in feature 418A. Each of the trailingfeatures 418B can have a shape that is more negative than the shape ofthe lead-in features, meaning the trailing features 418B slope moretowards the adjacent cantilever spring 416 than the lead-in features418A. The more negative shape of the trailing features 418B allowsstronger torques to be applied in the loosening direction than in thetightening direction.

Upon application of a loosening torque, e.g., a counter clockwise torquein the example of FIGS. 4A-4D, to the screw head 406, the cantileversprings 416 engage the trailing features 418B of each cam 418 and applythe loosening torque to the shaft 402 to loosen the thumbscrew 400. Asused herein, “loosening torque” is the opposite of “tightening torque”and refers to a torque that tends to loosen a screw or other threadedfastener out from a device having a tapped hole.

In the example of FIG. 4D, the loosening torque can exceed thepredetermined maximum torque in magnitude due to the negative shape ofthe trailing features 418B. Accordingly, the torque limiter ofthumbscrew 400 can function to limit torque in only the tighteningdirection, without limiting torque in the loosening direction in someembodiments.

As already mentioned above, the predetermined maximum torque of thetorque limiter may depend on the quantity of cantilever springs 416 andcams 418 included in the thumbscrew 400. Alternately or additionally,the predetermined maximum torque may depend on one or more of the lengthL (FIG. 4C) of each cantilever spring 416, the thickness T (FIG. 4D) ofeach cantilever spring 416, the material(s) the cantilever springs 416are made of, the quantity of the cantilevers springs 416, thecoefficient of static friction between the cantilever springs 416 andcams 418, the distance D (FIG. 4D) that each cam 418 radially protrudesfrom the second end 402B of shaft 402, the shape of the lead-in features418A, the coefficient of static friction between the cams 418 and thecantilever springs 416, or the like or any combination thereof.Thumbscrew designers can therefore engineer a thumbscrew for a desiredpredetermined maximum torque by appropriately selecting one or more of:the length L and/or thickness T of the cantilever springs 416, thematerial(s) the cantilever springs 416 are made of, the quantity of thecantilever springs 416, the coefficient of static friction between thecantilever springs 416 and cams 418, the distance D of each cam 418, theshape of the lead-in features 418A, or the coefficient of staticfriction between the cams 418 and the cantilever springs 416.

The thumbscrew 400 can optionally include an extension formed in thefirst end 402A, such as extension 226 of FIG. 2A, for use in protectinga module connector of a pluggable module in which the thumbscrew 400 isimplemented. Accordingly, the thumbscrew 400 can be implemented in themodule 200 of FIG. 2A. Alternately or additionally, the thumbscrew 400can be implemented in the module 300 of FIG. 3A in conjunction withguides 310, 312 having extensions 310A, 312A for protecting moduleconnector 308. Alternately or additionally, the thumbscrew 400 can beimplemented in other pluggable modules or other environments altogether.

V. HOST

Returning briefly to FIG. 1, and as already mentioned, the host device104 of FIG. 1 includes a front panel 108, host bezel assembly 110, hostPCB 112, host guides 114A, 114B, and host connector 116. Briefly, thefront panel 108 defines an opening configured to receive the module 102in a plugging direction. As used herein, “plugging direction” refers tothe direction in which the module 102 is plugged into the host device104. In the example of FIG. 1, the plugging direction corresponds to thenegative z-direction.

A. Host Bezel Assembly

Turning briefly to FIG. 5, one example of a host bezel assembly 500 isdisclosed that may correspond to the host bezel assembly 110 of FIG. 1.FIG. 5 illustrates an exploded perspective view of host bezel assembly500. The host bezel assembly 500 of FIG. 5 includes a front bezel 502,EMI gasket 504, and rear bezel 506. The host bezel assembly 500 definesan opening through which a pluggable module can be plugged into a hostdevice.

The front bezel 502 includes a rim 508. An EMI collar (e.g., EMI collar236, 328 of FIG. 2A or 3A) of a pluggable module inserted through thehost bezel assembly 500 is configured to contact the interior surface ofthe rim 508 in a wiping motion to form an EMI shield at the front of thepluggable module.

The front bezel 502 further includes a plurality of front bezel guides510, 512, each front bezel guide including a guide channel 510A, 512A,respectively. The front bezel guides 510, 512, and more specifically,the guide channels 510A, 512A, are configured to receive guiderails of apluggable module. For instance, guide channel 510A can receive guiderail210 of module 200 (FIG. 2A) or guiderail 310 of module 300 (FIG. 3A),while guide channel 512A can receive guiderail 212 of module 200 orguiderail 312 of module 300. The front bezel guides 510, 512 areconfigured to extend through the EMI gasket 504 and rear bezel 506.

A plurality of through-holes (not shown) are formed at the four insidecorners of the front bezel 502 where the rim 508 joins the front bezelguides 510, 512. The rear bezel 506 includes a corresponding pluralityof through-holes 514A-514D. The front bezel 502 through-holes (notshown) and rear bezel 506 through-holes 514A-514D are configured toreceive fasteners for coupling the front bezel 502 to the rear bezel 506through a host front panel, such as front panel 108 of FIG. 1.

The rear bezel 506 further includes portions 516, 518 that areconfigured to be engaged by hook features on corresponding host guidesto partially secure the host guides to the bezel assembly 500.

In some embodiments, the host bezel assembly 500 allows a host PCB tofloat. For instance, with combined reference to FIGS. 1 and 5, the hostbezel assembly 500 can allow the host PCB 112, to float with respect tothe front panel 108 in the plugging direction while remaining alignedwith the front panel 108 in directions normal to the plugging direction,e.g., in the x- and y-directions. Additional aspects regarding hostbezel assemblies that can be implemented in CFP and other mechanicalplatforms are disclosed in U.S. patent application Ser. No. 12/273,069,filed Nov. 18, 2008 and entitled FLOATING FRONT ENCLOSURE FOR PLUGGABLEMODULE (referred to herein as “the '069 application”). The '069application is herein incorporated by reference in its entirety.

Alternately or additionally, a unitary host bezel can be implemented inthe host device 104 of FIG. 1, rather than a host bezel assembly 110 or500. According to this embodiment, the unitary host bezel can includethrough-holes for receiving fasteners for securing corresponding hostguides directly to the unitary host bezel. Additional aspects regardingexample unitary host bezels that can be implemented in CFP and othermechanical platforms are disclosed in the '027 application.

B. Host Guide

Turning briefly to FIG. 6, one example of a host guide 600 is disclosedthat may correspond to one or both of the host guides 114A, 114B ofFIG. 1. The host guide 600 is configured to guide a pluggable modulewhen plugged into a host device in which the host guide 600 isimplemented and can include a channel 602 configured to receive aguiderail of the pluggable module. For instance, when host guide 600 isimplemented as host guide 114A of FIG. 1, the channel 602 can receivethe guiderail 210 of module 200 (FIG. 2A) or the guiderail 310 of module300 (FIG. 3A). Alternately, when host guide 600 is implemented as hostguide 114B of FIG. 1, the channel 602 can receive the guiderail 212 ofmodule 200 (FIG. 2A) or the guiderail 312 of module 300 (FIG. 3A).

The host guide 600 is configured to be rigidly secured to a host PCB andto be used in belly-to-belly configurations with itself. Further, thehost guide 600 can be configured to float with respect to acorresponding host bezel assembly. For instance, the host guide 600includes a plurality of hook features 604, 606, 608, 610 configured toengage corresponding portions of a host bezel assembly, e.g., portions516 and 518 of the host bezel assembly 500 of FIG. 5. When host guide600 is implemented as host guide 114A of FIG. 1, hook features 604, 606are configured to engage the portion 516 of host bezel assembly 500 ofFIG. 5. When host guide 600 is implemented as host guide 114B of FIG. 1,hook features 608, 610 are configured to engage the portion 518 of hostbezel assembly 500 of FIG. 5.

Basically, the hook features 604-606 or 608-610 ensure that a portion ofthe host guide 600, e.g. the hook features 604-606 or 608-610, remaindisposed within the opening defined by the host bezel assembly, whilestill allowing the host guide 600 and the host PCB to float with respectto the host bezel assembly in the plugging direction. By ensuring that aportion of the host guide 600 remains in the opening defined by the hostbezel assembly, the host guide 600 and host PCB can maintain alignmentwith the host bezel assembly in directions normal to the pluggingdirection.

Alternately or additionally, host guides can be implemented that arerigidly secured to a host bezel assembly and host PCB in a host devicein which the host guide is implemented.

Additional aspects regarding example host guides that can be implementedin CFP and other mechanical platforms are disclosed in the '027application and the '069 application.

C. Host Connector

With combined reference to FIGS. 2A-2C and 7A, one example of a hostconnector 700 is disclosed that may correspond to the host connector 116of FIG. 1. In some embodiments, the host connector 700 can beimplemented with the module 200 of FIG. 2A. The host connector 700 canbe coupled to a host PCB of a host device in which the host connector700 is implemented and is configured to provide an electrical interfacebetween module 200 and the host PCB. As shown in FIG. 7, the hostconnector 700 includes a connector core 702 defining a recessed slot forreceiving module connector 208, a one-piece connector cover 704 defininga cavity configured to receive the connector core 702, and a pluralityof EMI gaskets 706, 708, one each disposed on a front face and bottomface of the connector cover 704 to form EMI shields at interfaces of thehost connector 700 with the module 200 and host PCB.

Each of the connector core 702 and connector cover 704 can include oneor more posts 710, 712, 714 configured to be received in through-holeson the host PCB for properly aligning the connector core 702 andconnector cover 704 with the host PCB during assembly. The connectorcore 702 includes a plurality of contacts 716 configured to beelectrically coupled to contact pads of the host PCB. The contacts 716can be partially enclosed within a plurality of chicklets, each chickletenclosing two contacts 716 in some embodiments. The chicklets caninclude cutaway profiles to provide solder joint visibility duringassembly.

A plurality of asymmetrically positioned through-holes 718A, 718B andasymmetrically positioned tapped holes 720A, 720B can be defined in theconnector cover 704 to allow the host connector 700 to be used inbelly-to-belly configurations with duplicates of itself. The connectorcover 704 further includes a second plurality of tapped holes 722A, 722Bconfigured to receive threaded portions 222, 224 of thumbscrews 214, 216for threadably securing the module 200 directly to the host connector700.

In some embodiments, the front face of connector cover 704 acts as ahard stop within the host device for the module 200. Further, the tappedholes 722A, 722B allow the module 200 to be directly fastened to theconnector cover 704 via thumbscrews 214, 216. Direct fastening of themodule 200 to the host connector 700 can protect the connector core 702from mechanical damage caused by external stress in some embodiments.Alternately or additionally, directly securing the module 200 to thehost connector 700 can reduce tolerance stack-up between the hostconnector 700 and module connector 208 and can allow use of anelastomeric EMI gasket 706 at the interface of the module 200 with thehost connector 700, in contrast to conventional mechanical platformswhere the pluggable module is directly secured to the front panel of thehost device.

Turning now to FIG. 7B in combination with FIGS. 3A and 3B, a secondexample of a host connector 750 is disclosed that may correspond to thehost connector 116 of FIG. 1. In some embodiments, the host connector750 can be implemented with the module 300 of FIGS. 3A and 3B, forinstance. The host connector 750 can include a connector core 752, aone-piece connector cover 754, and a plurality of EMI gaskets 756, 758.

Some of the aspects of connector core 752, connector cover 754, and EMIgaskets 756, 758 of FIG. 7B may be similar to those of the connectorcore 702, connector cover 704, and EMI gaskets 706, 708 of FIG. 7A,while other aspects may be different. For instance, the connector cover754 of FIG. 7B includes one or more posts 760, 762, a plurality ofasymmetrically positioned through-holes 764A, 764B, and a plurality ofasymmetrically positioned tapped holes 766A, 766B.

In contrast to the connector cover 704 of FIG. 7A, however, theconnector cover 754 includes a plurality of slots 768A, 768B formed inthe connector cover 754 to accommodate the extensions 310A, 312A of themodule 300 of FIG. 3A. The connector cover 754 further includes a secondplurality of tapped holes 770A, 770B configured to receive threadedportions 318, 320 of thumbscrews 314, 316 for threadably securing themodule 300 directly to the connector cover 754. Alternately oradditionally, the connector cover 754 can include a plurality of tappedinserts, nuts, or the like, disposed in the slots 768A, 768B forreceiving threaded portions 318, 320 of thumbscrews 314, 316.

Additional aspects regarding example host connectors that can beimplemented in CFP and other mechanical platforms are disclosed in the'027 application.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A pluggable module, comprising: a shell defining a cavity withinwhich a printed circuit board and one or more components are disposed,the shell including a front, back, first side, and second side; a moduleconnector operatively connected to the printed circuit board near theback of the shell and extending from within the cavity to outside theshell through an opening defined in the back of the shell, the moduleconnector configured to operatively couple the pluggable module to ahost device; and one or more thumbscrews housed within one or moreportions of the shell and configured to threadably secure the pluggablemodule to the host device, each of the one or more thumbscrewscomprising a torque limiter.
 2. The pluggable module of claim 1, furthercomprising: protecting means for protecting a portion of the moduleconnector extending outside the cavity from damage; and a firstguiderail defined in the first side and a second guiderail defined inthe second side, each of the first and second guiderails extending fromthe front of the shell to the back of the shell.
 3. The pluggable moduleof claim 2, wherein the protecting means comprise a first portion of thefirst guiderail and a second portion of the second guiderail, the firstand second portions extending outwardly beyond a back end of the moduleconnector.
 4. The pluggable module of claim 2, wherein a firstthumbscrew is housed within the first guiderail and a second thumbscrewis housed within the second guiderail, the protecting means comprising aportion of each of the first and second thumbscrews extending outwardlybeyond a back end of the module connector.
 5. The pluggable module ofclaim 1, wherein each thumbscrew comprises: a screw head defining anopening and including one or more resilient members extending outwardfrom a base of the screw head; and a shaft defining a first endincluding a threaded portion and a second end including one or more camsradially protruding from the second end, the second end extending atleast partially into the opening defined by the screw head, wherein thetorque limiter comprises the one or more resilient members and the oneor more cams.
 6. A thumbscrew for securing a pluggable module to a hostdevice, comprising: a screw head defining an opening; a shaft defining afirst end and a second end, the first end including a threaded portionconfigured to threadably engage a tapped hole of a host device and thesecond end extending at least partially into the opening; and a torquelimiter that substantially prevents application of tightening torquesthat exceed a predetermined maximum torque to the shaft when thethreaded portion threadably engages the tapped hole of the host device.7. The thumbscrew of claim 6, further comprising: a notch formed in theshaft; and a retaining clip cooperating with the notch to substantiallyconfine the second end of the shaft within the opening of the screwhead.
 8. The thumbscrew of claim 6, further comprising an extensionformed in the shaft at the first end, the extension configured tocooperate with a shell of a pluggable module in which the thumbscrew isimplemented to form a protective barrier around a connector of thepluggable module.
 9. The thumbscrew of claim 6, wherein the torquelimiter comprises one or more cantilever springs extending from a baseof the screw head and one or more cams radially protruding from thesecond end of the shaft.
 10. The thumbscrew of claim 9, wherein the oneor more cantilever springs selectively engage the one or more cams andapply a tightening torque applied to the screw head to the shaftdepending on whether the tightening torque exceeds the predeterminedmaximum torque.
 11. The thumbscrew of claim 9, wherein the screw head,shaft, or both, comprise injection molded metal, forged metal, machineturned metal, or broached metal.
 12. The thumbscrew of claim 9, whereinthe predetermined maximum torque depends on one or more of: a length ofeach of the one or more cantilever springs; a thickness of each of theone or more cantilever springs; a material from which each of the one ormore cantilever springs is made; a quantity of the one or morecantilever springs; or a coefficient of static friction between the oneor more cantilever springs and the one or more cams.
 13. The thumbscrewof claim 9, wherein each of the one or more cams comprises a lead-infeature and is characterized by a distance that the cam radiallyprotrudes from the second end.
 14. The thumbscrew of claim 13, whereinthe predetermined maximum torque depends on one or more of: the distancethat each of the one or more cams radially protrudes from the secondend; a shape of the lead-in feature; a quantity of the one or more cams;or a coefficient of static friction between the one or more cams and theone or more cantilever springs.
 15. The thumbscrew of claim 13, whereineach of the one or more cams further comprises a trailing featureoppositely disposed from a lead-in feature of the cam, the one or morecantilever springs configured to engage a trailing feature of acorresponding cam and apply a loosening torque applied to the screw headto the shaft.
 16. The thumbscrew of claim 13, wherein when a tighteningtorque that exceeds the predetermined maximum torque is applied to thescrew head, the cantilever springs resiliently deflect up and over thelead-in features to disengage from the cams.
 17. A thumbscrew forsecuring a pluggable module to a host device, comprising: a shaftdefining a first end and a second end oppositely disposed from the firstend; a threaded portion formed in the first end and configured tothreadably secure a pluggable module to a host device, the pluggablemodule including a module connector configured to mate with a hostconnector of the host device; and a head disposed on the second end ofthe shaft and configured to apply at least some torque applied to thehead to the shaft, wherein the first end of the shaft is configured tocooperate with a shell of the pluggable module to form a protectivebarrier for the module connector.
 18. The thumbscrew of claim 17,wherein the thumbscrew comprises hardened steel and is configured toabsorb impact forces to protect the module connector.
 19. The thumbscrewof claim 17, wherein the head is integrally formed in the shaft at thesecond end.
 20. The thumbscrew of claim 17, wherein the head isseparable from the shaft and defines an opening configured to at leastpartially receive the second end of the shaft, the head including one ormore cantilever springs configured to selectively engage one or morecams formed in the second end of the shaft and to apply tighteningtorques applied to the head that do not exceed a predetermined maximumtorque to the shaft.